They break because there is no volute in the area where the headstock meets the neck.. Way too thin in that critical area..
I saw a LP headstock snap off when the Guitarist turned around and banged it on a mike stand!
You can only imagine how peeved the guy was, it was such a sweet sounding Axe and cost him quite a lot of money as it was a early 60's Gold Top model in pristine condition.....